<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
  <title>Reference for filter linked to local-ref URL</title>
  <defs>
    <filter id="blurFilter" x="-10" y="-10" width="100" height="100">
        <feGaussianBlur in="SourceGraphic" stdDeviation="10" />
    </filter>
  </defs>
  <rect x="10" y="10" width="80" height="80" fill="blue" filter="url(#blurFilter)"/>
  <rect x="10" y="110" width="80" height="80" fill="blue" filter="url(#blurFilter)"/>
  <rect x="10" y="210" width="80" height="80" fill="blue" filter="url(#blurFilter)"/>
</svg>